Simplify the following expression: ${-5(3+3p)+9(p-7)}$
Solution: Distribute the ${-5}$ into the first set of parentheses: $ {-5(}\gray{3+3p}{)} + 9(p-7) $ $ {-15-15p} + 9(p-7) $ Distribute the ${9}$ into the parentheses: $ -15-15p + {9(}\gray{p-7}{)} $ $ -15-15p + {9p-63} $ Rewrite the expression to group the ${p}$ terms and numeric terms: $ {-15p + 9p} {-15 - 63}$ Combine the ${p}$ terms: $ {-6p} {-15 - 63}$ Combine the numeric terms: $ {-6p} {-78}$ The simplified expression is $-6p-78$